According to existing practice of diathermy therapy at the 2.45 GHz band, only spaced external applicators are used for radiating the tissue under treatment. Since the applicator is spaced from the patient's tissue, the radiated energy is not confined to the prescribed tissue area but also irradiates uprescribed tissue of the patient, as well as the operator and other persons in the vicinity of the diathermy machine, causing the possibility of exposing the operator and other persons from exposure to the hazardous levels of energy fields.